This invention relates to a method and an apparatus for recording, on a recording medium such as a magnetic tape, a received signal of a digital broadcasting or a digital output signal from another digital video tape recorder.
In digital television broadcasting, a digital signal which has gone through an information compression process is transmitted. For efficient use of the transmission line, the transmission rate of the digital signal differs with the kinds of video sources, and even in the transmitted digital signal of the same image source, the transmission rate varies from moment to moment.
The digital video tape recorder converts an analog video signal into a digital signal, and records the video signal on a magnetic tape in the form of a digital signal. The transmission rate of the output digital signal of the digital video tape recorder differs from the transmission rate of the transmitted signal of digital television broadcasting.
A digital signal recording apparatus for recording a compressed digital video signal on a magnetic tape with a rotary head is revealed in Japanese Patent Application Laid-Open No. JP-A-5-174496.
Apparatus for recording on a recording medium a compressed digital signal in which the transmission rate and the data intervals are unfixed has not been developed. Nor has a recording method been developed which can selectively record signals of different transmission rates in a single recording apparatus.
A home use digital video tape recorder for recording a compressed digital video signal on a magnetic tape with a rotary head is reported in pages 137 to 150 of "Data Compression and Digital Modulation" published by Nikkei BP. This home use digital video tape recorder uses a high-performance metal-evaporated tape on a special-purpose cassette, and records a compressed digital video signal of 24.948 Mbps and digital audio signals of two channels (1.536 Mbps) at the head rotating speed of 9,000 rpm and at the recording rate of 41.85 Mbps. Signals of such high transmission rates cannot be recorded by the prior art on a conventional analog VTR in general use. The reason is that since the rotary head speed of the analog signal VTR is 1,800 rpm and an oxide tape is used, it is difficult to record a digital signal at a recording rate of 20 Mbps or higher. In addition, the cassette for the analog VTR is in a shape different from that of the digital VTR written in the above-mentioned literature.